Systems for generating a liquid aerosol

ABSTRACT

An aerosol generating system including a housing defining an airflow outlet; a liquid aerosol-forming substrate; an aerosol generator, configured to generate an aerosol from the liquid aerosol-forming substrate; a perforated plate disposed between the aerosol generator and the airflow outlet, the perforated plate defining a plurality of apertures extending through the perforated plate; and an electrode disposed between the aerosol generator and the perforated plate, wherein the perforated plate is electrically conductive, and wherein the electrode and the perforated plate are configured to generate an electrical potential.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of and claims priority under35 U.S.C. §120 to U.S. Pat. Application No. 16/353,469, filed on Mar.14, 2019, which claims priority to, international application numberPCT/EP2018/081980, filed on Nov. 20, 2018, which claims priority toEuropean patent application number 17204740.9, filed on Nov. 30, 2017,the entire contents of each of which are incorporated herein byreference.

FIELD

Example embodiments relate to aerosol-generating systems including aperforated plate disposed between an aerosol generator and an airflowoutlet. The example embodiments also relate to aerosol-generatingsystems including and aerosol charging circuit including an electrodearranged for fluid communication with an aerosol.

DESCRIPTION OF RELATED ART

Devices for generating aerosols are known in the art. Such systemstypically heat a liquid to vaporise the liquid and produce an aerosol.Such devices typically include a liquid storage portion or reservoir forholding a supply of a liquid aerosol forming substrate, or “e-liquid”,and a heater for heating the e-liquid to generate an aerosol. Suchdevices also include an airflow path in communication with the heater sothat the aerosol can be conveyed along the airflow path and exit thedevice.

The quality of the aerosol generated by known devices can be assessedusing a number of different factors. Factors may include quantity ofaerosol generated, density of droplets within the aerosol, temperatureof the aerosol and speed of delivery of the aerosol.

SUMMARY

At least one example embodiment relates to an aerosol generating system.

In one embodiment, the aerosol generating system including a housingdefining an airflow outlet; a liquid aerosol-forming substrate; anaerosol generator, configured to generate an aerosol from the liquidaerosol-forming substrate; a perforated plate disposed between theaerosol generator and the airflow outlet, the perforated plate defininga plurality of apertures extending through the perforated plate; and anelectrode disposed between the aerosol generator and the perforatedplate, wherein the perforated plate is electrically conductive, andwherein the electrode and the perforated plate is configured to generatean electrical potential.

In one embodiment, the perforated plate consists of a first plurality ofparallel filaments and a second plurality of parallel filaments, thefirst plurality of filaments orthogonal to the second plurality offilaments so that the plurality of apertures is a grid of apertures.

In one embodiment, the electric potential difference between theelectrode and the perforated plate is between 0.5 kilovolts and 30kilovolts.

In one embodiment, the spacing between the electrode and the perforatedplate is between 1 millimetre and 50 millimetres.

In one embodiment, the aerosol generating system further including acontrol circuit connected to the perforated plate and configured toallow measurement of an electrical current flowing in the perforatedplate during use.

In one embodiment, the aerosol generating system including a housingdefining an airflow outlet; a liquid aerosol-forming substrate; a powersupply; a controller; an aerosol generator configured to generate anaerosol from the liquid aerosol-forming substrate; an aerosol chargingcircuit including a circuit ground and an electrode arranged for fluidcommunication with aerosol generated by the aerosol generator, whereinthe controller is configured to control a supply of electrical powerfrom the power supply to the electrode to charge the electrode to apotential difference of between 0.5 kilovolts and 30 kilovolts withrespect to the circuit ground; and a perforated plate disposed betweenthe electrode and the airflow outlet, the perforated plate defining aplurality of apertures extending through the perforated plate.

In one embodiment, the electrode is a nozzle configured to directaerosol to the airflow outlet.

In one embodiment, the separation between the electrode and theperforated plate is between 1 millimetre and 50 millimetres.

In one embodiment, the perforated plate is electrically connected to thecircuit ground.

In one embodiment, the controller is connected to the perforated plateand configured to allow measurement of an electrical current flowing inthe perforated plate during use.

In one embodiment, the perforated plate consists of a first plurality ofparallel filaments and a second plurality of parallel filaments, thefirst plurality of filaments orthogonal to the second plurality offilaments so that the plurality of apertures is a grid of apertures.

In one embodiment, the aerosol generating system further including afirst reservoir containing the liquid aerosol-forming substrate and asecond reservoir containing an ionizable liquid.

In one embodiment, the electrode is two coaxial nozzles including afirst nozzle configured to eject liquid aerosol-forming substrate fromthe first reservoir and a second nozzle configured to eject ionizableliquid from the second reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

Features described in relation to one example embodiment may also beapplicable to other example embodiments. Example embodiments will now bedescribed, by way of example only, with reference to the figures.:

FIG. 1 illustrates a schematic representation of a first embodiment ofan aerosol generating system, in accordance with an example embodiment;

FIG. 2 illustrates an aerosol generator arrangement, in accordance withan example embodiment;

FIG. 3 illustrates an aerosol generator arrangement, in accordance withan example embodiment;

FIG. 4 illustrates a heater arrangement, in accordance with an exampleembodiment;

FIG. 5 illustrates a perforated plate, in accordance with an exampleembodiment;

FIG. 6 illustrates a schematic representation of an aerosol generatingsystem, in accordance with an example embodiment;

FIG. 7 illustrates a schematic representation an electrode structure, inaccordance with an example embodiment;

FIG. 8 illustrates a schematic representation of a an aerosol generatingsystem, in accordance with an example embodiment;

FIG. 9 illustrates a schematic representation of a an aerosol generatingsystem, in accordance with an example embodiment;

FIG. 10 illustrates a schematic representation of a an aerosolgenerating system, in accordance with an example embodiment; and

FIG. 11 illustrates a schematic representation of the nozzleconfiguration of the aerosol generating system of FIG. 10 , inaccordance with an example embodiment.

DETAILED DESCRIPTION

Some detailed example embodiments are disclosed herein. However,specific structural and functional details disclosed herein are merelyrepresentative for purposes of describing example embodiments. Exampleembodiments may, however, be embodied in many alternate forms and shouldnot be construed as limited to only the example embodiments set forthherein.

Accordingly, while example embodiments are capable of variousmodifications and alternative forms, example embodiments thereof areshown by way of example in the drawings and will herein be described indetail. It should be understood, however, that there is no intent tolimit example embodiments to the particular forms disclosed, but to thecontrary, example embodiments are to cover all modifications,equivalents, and alternatives falling within the scope of exampleembodiments. Like numbers refer to like elements throughout thedescription of the figures.

It should be understood that when an element or layer is referred to asbeing “on,” “connected to,” “coupled to,” or “covering” another elementor layer, it may be directly on, connected to, coupled to, or coveringthe other element or layer or intervening elements or layers may bepresent. In contrast, when an element is referred to as being “directlyon,” “directly connected to,” or “directly coupled to” another elementor layer, there are no intervening elements or layers present. Likenumbers refer to like elements throughout the specification. As usedherein, the term “and/or” includes any and all combinations of one ormore of the associated listed items.

It should be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, elements, regions,layers and/or sections, these elements, elements, regions, layers,and/or sections should not be limited by these terms. These terms areonly used to distinguish one element, element, region, layer, or sectionfrom another region, layer, or section. Thus, a first element, element,region, layer, or section discussed below could be termed a secondelement, element, region, layer, or section without departing from theteachings of example embodiments.

Spatially relative terms (e.g., “beneath,” “below,” “lower,” “above,”“upper,” and the like) may be used herein for ease of description todescribe one element or feature’s relationship to another element(s) orfeature(s) as illustrated in the figures. It should be understood thatthe spatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the term “below” may encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

The terminology used herein is for the purpose of describing variousexample embodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an,” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“includes,” “including,” “comprises,” and/or “comprising,” when used inthis specification, specify the presence of stated features, integers,steps, operations, elements, and/or elements, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, elements, and/or groups thereof.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures) of exampleembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, example embodiments should not be construed aslimited to the shapes of regions illustrated herein but are to includedeviations in shapes that result, for example, from manufacturing.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, including those defined incommonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand will not be interpreted in an idealized or overly formal senseunless expressly so defined herein.

General Methodology

It would be desirable to provide an aerosol-generating system thatfacilitates delivery of an aerosol that may provide an improved adultvaper’s experience. It would be desirable to provide anaerosol-generating system that facilitates consistent delivery of anaerosol.

Specific Example Embodiments

According to a first aspect of the example embodiments there is providedan aerosol generating system including a housing defining an airflowoutlet, and a liquid aerosol-forming substrate. The system also includesan aerosol generator configured to form an aerosol from the liquidaerosol-forming substrate, and a perforated plate disposed between theaerosol generator and the airflow outlet. The perforated plate defines aplurality of apertures extending through the perforated plate.

As used herein, the term ‛aerosol-forming substrate’ relates to asubstrate capable of releasing volatile compounds that can form anaerosol. Such volatile compounds may be released by heating theaerosol-forming substrate or other aerosolising means. A suitablesubstrate could be in liquid form, such as an e-liquid.

The present inventors have recognised that a property of an aerosol thatmay affect an adult vaper’s experience is the average droplet size ofthe aerosol. In particular, the present inventors have recognised thatan aerosol including an average droplet size that is too large mayadversely affect an adult vaper’s experience .

Aerosol-generating systems according to the example embodiments includea perforated plate between an aerosol generator and an airflow outlet.Therefore, during use, aerosol produced by the aerosol generator mustpass through the perforated plate before it can be inhaled. Any dropletsof the aerosol that are larger than the apertures in the perforatedplate may be prevented from passing through the perforated plate.Therefore, the perforated plate may be configured to limit the maximumdroplet size of the aerosol delivered. For example, a droplet of theaerosol that is larger than an aperture in the perforated plate can beblocked by the plate that defines each aperture.

Controlling the maximum droplet size of an aerosol that is generated bythe aerosol generating system may allow the perforated plate tofacilitate consistent delivery of an aerosol. The consistent dropletsize of aerosols delivered by aerosol generating systems according tothe example embodiments provides a consistent adult vaper experience.

The perforated plate may include a sheet material including theplurality of apertures extending through the sheet material. The sheetmaterial may be a single element. The plurality of apertures may beformed in the sheet material using any suitable process. The pluralityof apertures may be formed using at least one of drilling, punching,laser perforation, and electron discharge machining.

The perforated plate may include a composite structure, formed ofmultiple elements that together define a plurality of openings extendingthrough the structure, wherein the plurality of openings form theplurality of apertures. The perforated plate may include a plurality ofelongate elements connected to form a planar composite structure. Theperforated plate may include an array of filaments or threads, whereineach of the plurality of apertures is formed by an opening definedbetween consecutive filaments or threads.

The array of filaments may be formed of a plurality of parallelfilaments defining elongate apertures therebetween. As used, herein, theterm “parallel” means substantially parallel, within plus or minus 10degrees, or within plus or minus 5 degrees. The array of filaments maybe formed of a first plurality of parallel filaments, and a secondplurality of parallel filaments, the first plurality of filamentsorthogonal to the second plurality of filaments. The plurality ofapertures may be a grid of apertures. The first plurality of parallelfilaments and the second plurality of parallel filaments may lie withina single plane.

Each of the filaments that forms the perforated plate may have a maximumthickness of between about 10 micrometres and about 500 micrometres.Providing filaments having a maximum thickness within this range mayblock some droplets of aerosol.

The perforated plate may include a mesh.

The aerosol generator may include a heater. During use, the heatervaporises liquid aerosol forming substrate. The heater may be anelectric heater.

The heater may be a resistive heater.

The heater may be an inductive heater. The aerosol generator may furtherinclude a susceptor, wherein the inductive heater is configured toinductively heat the susceptor during use. The inductive heater may bepositioned around a portion of the susceptor.

The aerosol generating system may include a reservoir containing theliquid aerosol-forming substrate. The reservoir may be disposed withinthe housing.

The aerosol generator may be positioned at an outlet of the reservoir.The aerosol generating system may include a liquid transfer elementarranged to transfer liquid aerosol-forming substrate from the reservoirto the aerosol generator. The liquid transfer element may include atleast one of a wick or a capillary tube.

The aerosol generator may include a nozzle assembly. During use,droplets of liquid aerosol-forming substrate from the reservoir areejected through the nozzle. The aerosol generator may include apiezoelectric component. During use, the piezoelectric component ejectsdroplets of liquid aerosol-forming substrate through the nozzle. Thenozzle is in fluid communication with the reservoir. The nozzle may formpart of the reservoir. The piezoelectric component may be positionedinside the reservoir. The aerosol generator may include a mesh coveringan outlet of the nozzle. During use, liquid aerosol-forming substratepasses through the mesh as droplets of liquid aerosol-forming substrateare ejected from the nozzle outlet.

Each aperture of the perforated plate may have a maximum width within aplane defined by the perforated plate. The maximum width of eachaperture may be between about 10 micrometres and about 100 micrometres.Aerosol droplets with a diameter larger than about 100 micrometres maybe removed or resized into smaller droplets by apertures having amaximum width of less than about 100 micrometres. Apertures having amaximum width of greater than about 10 micrometres may facilitatesufficient airflow through the perforated plate to reduce or minimisethe condensation of aerosol droplets on the perforated plate.

Each of the apertures may be substantially square or substantiallyrectangular.

The housing may define an airflow channel extending between the aerosolgenerator and the airflow outlet. The perforated plate may extend acrossthe airflow channel. The perforated plate helps ensure that, during use,the aerosol generated by the aerosol generator passes through theperforated plate before the aerosol is inhaled via the airflow outlet.The perforated plate may define a plane, wherein the plane extendsorthogonally with respect to a longitudinal axis of the airflow channel.The plane may extend orthogonally with respect to a direction of airflowthrough the airflow channel during use.

The aerosol generator may be arranged to direct aerosol generated by theaerosol generator towards the perforated plate. Directing the generatedaerosol directly at the perforated plate may increase the speed of theaerosol droplets when they reach the perforated plate. Increasing thespeed of the droplets when they encounter the perforated plate mayfacilitate blocking of larger droplets as they pass through theapertures in the perforated plate. Increasing the speed of the dropletsmay reduce or minimise the collection and build-up of droplets on theperforated plate. Increasing the speed of the droplets may reduce orminimise the need for cleaning of the aerosol-generating system.

The perforated plate may be constructed from any suitable material. Theperforated plate may be formed from a polymer material. The perforatedplate may be formed from a metal. Suitable metals include steels. Theperforated plate may be formed from a stainless steel.

The aerosol generating system may further include an electrode disposedbetween the aerosol generator and the perforated plate, the electrodeconfigured to electrostatically charge the aerosol. When an electrode isprovided, the perforated plate may be electrically conductive, whereinthe aerosol-generating system is configured to generate an electricpotential difference between the electrode and the perforated plate.Alternatively, when an electrode is provided, the perforated plate maybe electrically insulating.

The droplets of the aerosol generated by the aerosol generator may beelectrostatically charged by the electrode such that the droplets ofaerosol are electrostatically attracted to the perforated plate. Theelectrostatic attractive forces accelerate the droplets towards theperforated plate. Accelerating the droplets of aerosol towards theperforated plate may increase the speed of the droplets passing throughthe perforated plate. This increased speed of the droplets mayfacilitate blocking of larger droplets as they pass through theperforated plate. This blocking of larger droplets may reduce orminimise the collection and build-up of droplets on the perforatedplate. These reduced or minimized collection and build-up of dropletsmay reduce or minimise the need for cleaning of the aerosol-generatingsystem.

The aerosol generating system may be configured to generate an electricpotential difference between the electrode and the perforated plate ofbetween about 0.5 kilovolts and about 50 kilovolts, between about 5kilovolts and about 15 kilovolts, or about 10 kilovolts. At the typicaldimensions of an aerosol-generating system, an electric potentialdifference below about 50 kilovolts may be insufficient to causebreakdown of the air within the system. An electrical potentialdifference above 0.5 kilovolts may be strong enough to providesufficient acceleration of the charged droplets of aerosol towards theperforated plate. The potential difference may be provided with the useof a transformer within the aerosol generating system. The potentialdifference may be provided with the use of at least one boost converter.

As pacing between the electrode and the perforated plate is betweenabout 1 millimetre and about 50 millimetres, or between about 3millimetres and about 10 millimetres. Spacings within these ranges mayreduce or minimise the risk of electrical breakdown of the air withinthe system, particularly when combined with the ranges of electricpotential difference defined herein. Spacings within the range ofbetween about 3 millimetres and about 10 millimetres may allowconstruction of the aerosol-generating system with a size that moreclosely resembles a cigarette. An aerosol generating system having asize that is similar to the size of a cigarette may allow theaerosol-generating system to be easily stored or transported in asimilar manner to a cigarette.

The perforated plate may be grounded with respect to the electrode.Grounding the perforated plate may allow aerosol droplets that have beencharged by the electrode to release their charge to the perforatedplate. Grounding the perforated plate may allow the aerosol dropletsdelivered to be neutral or not charged.

The perforated plate may not be grounded with respect to the electrode,such that the aerosol droplets retain their charge as they pass throughthe apertures in the perforated plate and charged aerosol droplets aredelivered.

The aerosol generating system may further include a control circuit.

In example embodiments in which the aerosol generator includes at leastone of an electric heater and a piezoelectric component, the controlcircuit may be configured to control a supply of electrical power to theelectric heater, the piezoelectric component, or both.

In example embodiments in which the aerosol-generating system include anelectrode, the control circuit may be configured to control a supply ofelectrical power to the electrode to generate an electric potentialdifferent between the electrode and the perforated plate. The controlcircuit may be configured to control a supply of electrical power to theperforated plate to facilitate the generation of an electric potentialdifference between the electrode and the perforated plate. The controlcircuit may be connected to the perforated plate and configured tomeasure an electrical current in the perforated plate during use.Measuring the electrical current in the perforated plate may provide anindication of a flow rate of aerosol through the perforated plate. Inother words, charged droplets of aerosol incident on the perforatedplate may generate an electrical current within the perforated plate.The rate at which charged droplets pass through the array will vary theelectrical current measured in the perforated plate. Measuring anelectrical current within the perforated plate during use may allow thecontrol circuit to estimate an amount of aerosol delivered. Anestimation of an amount of aerosol generated may allow the operation andefficiency of the aerosol generating system over time to be monitored.For example, an estimate of an amount of aerosol generated may be usedto estimate an amount of liquid aerosol-forming substrate remaining inthe aerosol generating system.

The liquid aerosol-forming substrate may include water.

The liquid aerosol-forming substrate may include an aerosol-former. Asused herein, the term “aerosol-former” refers to any suitable knowncompound or mixture of compounds that, in use, facilitates formation ofa dense and stable aerosol. Suitable aerosol-formers are well known inthe art and include, but are not limited to: polyhydric alcohols, suchas triethylene glycol, 1,3-butanediol and glycerine; esters ofpolyhydric alcohols, such as glycerol mono-, di- or triacetate; andaliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyldodecanedioate and dimethyl tetradecanedioate. Example aerosol formersare polyhydric alcohols or mixtures thereof, such as triethylene glycol,1 ,3-butanediol and, glycerine or polyethylene glycol.

The liquid aerosol-forming substrate may include at least one ofnicotine or a tobacco product. Additionally, or alternatively, theliquid aerosol-forming substrate may include another target compound fordelivery. In example embodiments in which the liquid aerosol-formingsubstrate includes nicotine, the nicotine may be included in the liquidaerosol-forming substrate with an aerosol-former.

The aerosol-generating system may include an airflow inlet. The airflowinlet is in fluid communication with the aerosol generator. During use,air enters the aerosol-generating system through the airflow inlet andexits the aerosol-generating system through the airflow outlet.

The aerosol-generating system may include at least one power supply. Inexample embodiments in which the aerosol generator includes at least oneof an electric heater and a piezoelectric component, the at least onepower supply may be configured to provide a supply of electrical powerto the electric heater, the piezoelectric component, or both.

In example embodiments in which the aerosol-generating system includesan electrode, the at least one power supply may be configured to providea supply of electrical power to the electrode to generate an electricpotential different between the electrode and the perforated plate. Theat least one power supply may be configured to provide a supply ofelectrical power to the perforated plate to facilitate the generation ofan electric potential difference between the electrode and theperforated plate.

The at least one power supply may include a first power supplyconfigured to provide a supply of electrical power to the aerosolgenerator and a second power supply configured to provide a supply ofelectrical power to the electrode.

In example embodiments in which the aerosol-generating system includes acontrol circuit, the control circuit may be configured to control asupply of electrical power from the at least one power supply to atleast one of the aerosol generator, the electrode and the perforatedplate.

The at least one power supply may include a battery, such as arechargeable lithium ion battery. The at least one power supply mayinclude another form of charge storage device such as a capacitor. Theat least one power supply may require recharging. The at least one powersupply may have a capacity that allows for the storage of enough energyfor one or more uses of the aerosol generating system. For example, theat least one power supply may have sufficient capacity to allow for thecontinuous generation of aerosol for a period of around six minutes,corresponding to the typical time taken to smoke a cigarette, or for aperiod that is a multiple of six minutes. In another example, the atleast one power supply may have sufficient capacity to allow for apredetermined number of puffs or discrete activations.

Some aspects or components of the aerosol generating system may beseparable, removable, or single-use and disposable. The system isconfigured for use to produce an inhalable aerosol when fully assembled,as further described herein. The aerosol generating system may include apower supply section and an aerosol generating section configured forattachment to the power supply section. In example embodiments in whichthe aerosol generating system includes at least one of a power supplyand a control circuit, the power supply and the control circuit may bepositioned in the power supply section. The liquid aerosol-formingsubstrate and the airflow outlet may be provided in the aerosolgenerating section. The aerosol generator and the perforated plate mayeach form part of the power supply section or the aerosol generatingsection.

According to a second aspect of the example embodiments there isprovided an aerosol generating system including a housing defining anairflow outlet; a liquid aerosol-forming substrate; a power supply; acontroller; an aerosol generator configured to generate an aerosol fromthe liquid aerosol-forming substrate; and an aerosol charging circuitincluding a circuit ground and an electrode arranged for fluidcommunication with aerosol generated by the aerosol generator, whereinthe controller is configured to control a supply of electrical powerfrom the power supply to the electrode to charge the electrode to apotential difference of between about 0.5 kilovolts and about 30kilovolts with respect to the circuit ground. The controller may beconfigured to charge the electrode to a potential difference of betweenabout 5 kilovolts and about 15 kilovolts, or about 10 kilovolts withrespect to the circuit ground.

During use, the electrode charges or ionizes droplets of the aerosolgenerated by the aerosol generator. Once the droplets are charged,repulsive forces are generated within the charged droplets. Theelectrostatic charges of each e-liquid particle within each dropletrepel each other, and the surface tension acting on the outer surface ofeach droplet hold the droplet together. The larger a droplet is, themore e-liquid particles there are contained within the droplet, and themore repulsive electrostatic forces there are within the droplet oncethe droplet is charged. At what is known as the Rayleigh Limit, theinternal repulsive forces overcome the surface tension forces and thedroplet breaks apart into multiple smaller droplets. This process isknown as Coulomb fission. The present inventors have appreciated thatcharging droplets of a generated aerosol such that droplets over amaximum, predetermined size reach their Rayleigh Limit and break apartinto smaller droplets provides a reliable and consistent mechanism tolimit the maximum size of aerosol droplets and provide a morehomogeneous aerosol. The precise value to which the droplets are chargedmay be chosen for a particular liquid aerosol aerosol-forming substrate.At the typical dimensions of an aerosol-generating system, an electricpotential difference below about 30 kilovolts may be insufficient tocause breakdown of the air within the system.

The present inventors have recognised that an adult vaper’s experiencemay be particularly favourable when the maximum droplet size of anaerosol is equal to or less than about 2 micrometres. The presentinventors have further recognised that, for typical liquidaerosol-forming substrates, an electrical potential difference of atleast about 0.5 kilovolts is sufficient to electrically charge dropletshaving a size of greater than about 2 micrometres to an electricalcharge exceeding the Rayleigh Limit.

The potential difference may be provided with the use of a transformerwithin the aerosol generating system. The potential difference may beprovided with the use of at least one boost converter.

The power supply may be a single power supply and the controller may beconfigured to control a supply of electrical power from the single powersupply to the aerosol generator and the aerosol charging circuit. Thepower supply may include first and second power supplies, wherein thecontroller is configured to control a supply of electrical power fromthe first power supply to the aerosol generator and to control a supplyof electrical power from the second power supply to the aerosol chargingcircuit.

The aerosol generator may include a heater. During use, the heatervaporises liquid aerosol forming substrate. The heater may be anelectric heater.

The heater may be a resistive heater.

The heater may be an inductive heater. The aerosol generator may furtherinclude a susceptor, wherein the inductive heater is configured toinductively heat the susceptor during use. The inductive heater may bepositioned around a portion of the susceptor.

The aerosol generating system may include a reservoir containing theliquid aerosol-forming substrate. The reservoir may be disposed withinthe housing.

The aerosol generator may be positioned at an outlet of the reservoir.The aerosol generating system may include a liquid transfer elementarranged to transfer liquid aerosol-forming substrate from the reservoirto the aerosol generator. The liquid transfer element may include atleast one of a wick or a capillary tube.

The aerosol generator may include a nozzle assembly. During use,droplets of liquid aerosol-forming substrate from the reservoir areejected through the nozzle. The aerosol generator may include apiezoelectric component. During use, the piezoelectric component ejectsdroplets of liquid aerosol-forming substrate through the nozzle. Thenozzle is in fluid communication with the reservoir. The nozzle may formpart of the reservoir. The piezoelectric component may be positionedinside the reservoir. The aerosol generator may include a mesh coveringan outlet of the nozzle. During use, liquid aerosol-forming substratepasses through the mesh as droplets of liquid aerosol-forming substrateare ejected from the nozzle outlet.

The aerosol generating system may include an internal airflow channel influid communication with the aerosol generator. The internal airflowchannel may extend between an airflow inlet and the airflow outlet.During use, the airflow passing through the airflow channel may pick upgenerated aerosol as the airflow passes the aerosol generator. Airflowcontaining the generated aerosol may pass out of the airflow outlet.Based on the positioning of the airflow inlet and airflow outlet, therelative positioning of the elements within the aerosol generatingsystem of the example embodiments may be defined according to whetherthey are upstream or downstream from other elements. The airflow inletis upstream of the airflow outlet. The aerosol generator is downstreamof the airflow inlet, and upstream of the electrode.

The electrode may be located downstream of the aerosol generator andupstream of the airflow outlet. The electrode may include at least oneof a ring electrode and a mesh electrode. During use, aerosol generatedby the aerosol generator may pass through the electrode.

The electrode may be a nozzle configured to direct aerosol to theairflow outlet. The nozzle may define a nozzle outlet through which theaerosol flows to the airflow outlet. The charged nozzle may create anelectric field in the surrounding region. In particular, the nozzleelectrode may create an electric field in the nozzle outlet. During use,the generated aerosol passes through the nozzle outlet, at which pointthe droplets of the aerosol are ionized. The nozzle configuration forthe electrode may ensure that all droplets of the aerosol must passclose to the electrode and therefore through the electric field. Thenozzle configuration may provide an efficient ionizing assembly. Inexample embodiments in which the aerosol generator includes a nozzleassembly, the aerosol generator nozzle and the electrode nozzle may bethe same nozzle.

In example embodiments in which the aerosol generating system includes areservoir for storing a liquid aerosol-forming substrate, the reservoirmay be a first reservoir. The aerosol generating system may furtherinclude a second reservoir for an ionizable liquid. The second reservoirmay contain an ionizable liquid. Some liquid aerosol-forming substratesthat may be for inhalation may not be easily ionized. An ionizableliquid may be more easily ionized than a given liquid aerosol-formingsubstrate. An ionizable liquid may be ionized at a lower potentialdifference than a given liquid aerosol-forming substrate. A largerproportion of an ionizable liquid may be ionized at a given potentialdifference than the proportion of a given liquid aerosol-formingsubstrate at the same potential difference. The ionizable liquid mayfacilitate ionization of the liquid aerosol-forming substrate. Theaerosol-generating system may be configured to combine ionizable liquidfrom the second reservoir with liquid aerosol-forming substrate from thefirst reservoir. The aerosol-generating system may be configured tocombine the ionizing liquid and the liquid aerosol-forming substratebefore aerosolisation of the liquid aerosol-forming substrate. Theaerosol generating system may be configured to combine the ionizingliquid and the liquid aerosol-forming substrate after aerosolisation ofthe liquid aerosol-forming substrate and upstream of the electrode. Theionizable liquid may be at least one of aerosolisable and volatile. Asuitable ionizable liquid may include ethanol.

In example embodiments in which the aerosol generator includes a nozzleassembly, the nozzle of the nozzle assembly may be formed of two coaxialnozzles. The two coaxial nozzles may include a first nozzle configuredto eject liquid aerosol-forming substrate from the first reservoir and asecond nozzle configured to eject ionizable liquid from the secondreservoir. The two coaxial nozzles may produce coaxial streams of liquidaerosol-forming substrate and ionizable liquid, one within the other.This may encourage mixing of the liquid aerosol-forming substrate andthe ionizable liquid. This may result in a more homogeneous mixture ofthe liquid aerosol-forming substrate and the ionizable liquid, which mayfacilitate charging of the droplets aerosol by the electrode.

The controller may be configured to control a supply of electrical powerto at least one of the first nozzle and the second nozzle. Thecontroller may be configured to control a same supply of electricalpower to the first and second nozzles to charge the first and secondnozzles to a same potential difference with respect to the circuitground. The controller may be configured to control a different supplyof electrical power to the first and second nozzles to charge the firstand second nozzles to different potential differences with respect tothe circuit ground. The controller may be configured to control a supplyof electrical power to only one of the first and second nozzles.

The aerosol-generating system may further include an electricallyconductive perforated plate positioned between the electrode and theairflow outlet. The perforated plate defines a plurality of aperturesextending through the perforated plate. The charged aerosol produced bythe aerosol generator and the electrode must pass through the perforatedplate before the aerosol can be inhaled. Any droplets of the aerosolthat are larger than the apertures defined within the perforated platemay be prevented from passing through the perforated plate. Therefore,the perforated plate may be configured to limit the maximum droplet sizeof the aerosol delivered.

The perforated plate may include any of the features of the perforatedplate described herein with respect to the first aspect of the exampleembodiments.

The aerosol-generating system may be configured so that, when theelectrode is charged to generate a potential difference between theelectrode and the circuit ground, a potential difference is alsogenerated between the electrode and the perforated plate. During use,the droplets of the aerosol that are electrostatically charged by theelectrode may be electrostatically attracted to the perforated plate.The electrostatic attractive forces accelerate the droplets towards theperforated plate. Accelerating the droplets of aerosol towards theperforated plate may increase the speed of the droplets passing throughthe perforated plate. Accelerating the droplets of aerosol mayfacilitate blocking of larger droplets as they pass through theperforated plate. Accelerating the droplets of aerosol may reduce orminimise the collection and build-up of droplets on the perforatedplate. Accelerating the droplets of aerosol may reduce or minimise theneed for cleaning of the aerosol-generating system.

The controller may be configured to control a supply of electrical powerto the perforated plate to facilitate the generation of an electricpotential difference between the electrode and the perforated plate.

The perforated plate may be connected to or form part of the circuitground of the aerosol charging circuit.

A spacing between the electrode and the perforated plate may be betweenabout 1 millimetre and about 50 millimetres, or between about 3millimetres and about 10 millimetres. Spacings within these ranges mayreduce or minimise the risk of electrical breakdown of the air withinthe system, and the effect may be increased when combined with theranges of electric potential difference according to the second aspectof the example embodiments. Spacings within the range of between about 3millimetres and about 10 millimetres may allow construction of theaerosol-generating system with a size that more closely resembles acigarette. An aerosol generating system having a size that is similar tothe size of a cigarette may allow the aerosol-generating system to beeasily stored or transported in a similar manner to a cigarette.

The controller may be connected to the perforated plate and configuredto measure an electrical current in the perforated plate during use.Measuring the electrical current in the perforated plate may provide anindication of a flow rate of aerosol through the perforated plate. Inother words, charged droplets of aerosol incident on the perforatedplate may generate an electrical current within the perforated plate.The rate at which charged droplets pass through the perforated platewill vary the electrical current measured in the perforated plate.Measuring an electrical current within the perforated plate during usemay allow the control circuit to estimate an amount of aerosoldelivered. Estimating the amount of aerosol delivered may allow theoperation and efficiency of the aerosol generating system over time tobe monitored. For example, an estimate of an amount of aerosol deliveredmay be used to estimate an amount of liquid aerosol-forming substrateremaining in the aerosol generating system.

The perforated plate may be electrically connected to the circuitground.

The liquid aerosol-forming substrate may include water.

The liquid aerosol-forming substrate may include an aerosol-former. Asused herein, the term “aerosol-former” refers to any suitable knowncompound or mixture of compounds that, in use, facilitates formation ofa dense and stable aerosol. Suitable aerosol-formers are well known inthe art and include, but are not limited to: polyhydric alcohols, suchas triethylene glycol, 1,3-butanediol and glycerine; esters ofpolyhydric alcohols, such as glycerol mono-, di- or triacetate; andaliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyldodecanedioate and dimethyl tetradecanedioate. Example aerosol formersare polyhydric alcohols or mixtures thereof, such as triethylene glycol,1,3-butanediol andglycerine or polyethylene glycol.

The liquid aerosol-forming substrate may include at least one ofnicotine or a tobacco product. Additionally, or alternatively, theliquid aerosol-forming substrate may include another target compound fordelivery. In example embodiments in which the liquid aerosol-formingsubstrate includes nicotine, the nicotine may be included in the liquidaerosol-forming substrate with an aerosol-former.

The power supply may include a first power supply configured to providea supply of electrical power to the aerosol generator and a second powersupply configured to provide a supply of electrical power to theelectrode.

The power supply may include a battery, such as a rechargeable lithiumion battery. The power supply may include another form of charge storagedevice such as a capacitor. The power supply may require recharging. Thepower supply may have a capacity that allows for the storage of enoughenergy for one or more uses of the aerosol generating system. Forexample, the power supply may have sufficient capacity to allow for thecontinuous generation of aerosol for a period of around six minutes,corresponding to the typical time taken to smoke a cigarette, or for aperiod that is a multiple of six minutes. In another example, the powersupply may have sufficient capacity to allow for a predetermined numberof puffs or discrete activations.

Some aspects or components of the aerosol generating system may beseparable, removable, or single-use and disposable. The system isconfigured for use to produce an inhalable aerosol when fully assembled,as further described herein. The aerosol generating system may include apower supply section and an aerosol generating section configured forattachment to the power supply section. The power supply and thecontroller may be positioned in the power supply section. The liquidaerosol-forming substrate and the airflow outlet may be provided in theaerosol generating section. The aerosol generator and the electrode mayeach form part of the power supply section or the aerosol generatingsection.

Example Structural Embodiments

FIG. 1 illustrates a schematic representation of a first embodiment ofan aerosol generating system, in accordance with an example embodiment.The aerosol generating system 10 includes a housing 12 with an airflowinlet 14 and an airflow outlet 16. Within the housing 12 is a powersupply 13 and control unit 18, a reservoir 20 of liquid aerosol-formingsubstrate 21, an aerosol generator 22, and a perforated plate 24.

The aerosol generator 22 in a first configuration is a tank 26, separatefrom the reservoir 20, but in fluid communication with the reservoir 20so that liquid aerosol-forming substrate 21 can flow from the reservoir20 to the tank 26 to be aerosolised. The tank 26 includes apiezoelectric component 28 and mesh 30 (see FIG. 2 ). Together, thepiezoelectric component 28 and the mesh 30 are configured to aerosolisethe liquid aerosol-forming substrate within the tank 26.

FIG. 2 illustrates an aerosol generator arrangement, in accordance withan example embodiment., When the piezoelectric component 28 is notexcited, liquid aerosol-forming substrate 21 from the reservoir 20 canenter the tank 26 through a one-way valve 32.

FIG. 3 illustrates an aerosol generator arrangement, in accordance withan example embodiment., When the piezoelectric component 28 is excited,the piezoelectric component 28 vibrates and compresses the liquidaerosol-forming substrate in the tank 26. The piezoelectric component 28is excited by passing alternating electric current through thepiezoelectric component 28. The electric current is provided by thepower supply 13 and the control unit 18. When excited, the piezoelectriccomponent 28 bends or flexes and the pressure in the tank 26 increases.The one-way valve 32 hinders or prevents the flow of liquidaerosol-forming substrate back through the one-way valve 32 and so thepressure within the tank 26 forces liquid aerosol-forming substratethrough the mesh 30, and out through a nozzle 34 as aerosol droplets. Inthis way the liquid aerosol-forming substrate 21 is aerosolised.

The aerosol generator 22 in a second configuration is a heater assembly36 configured to heat the liquid aerosol-forming substrate 21 so as tovaporise the liquid aerosol-forming substrate 21 and form an aerosol.

FIG. 4 illustrates a heater arrangement, in accordance with an exampleembodiment. The heater assembly 36 includes a wick 38 and a heater coil40. The wick 38 extends into the reservoir 20 to wick liquidaerosol-forming substrate from the reservoir 20 to the heater coil 40.The wick 38 may be a length of absorbent material or a capillary tube totransport the liquid aerosol-forming substrate via capillary action. Theheater coil 40 is powered by the power supply 13 and control unit 18.The heater coil 40 is a coil of resistive material, for example, ametal, which is resistively heated when an electrical current is passedthrough the heater coil 40. The power supply 13 and control unit 18 passelectrical current through the heater coil 40 to heat and volatise theliquid aerosol-forming substrate in the wick 38.

Alternatively, the heater assembly 36 could be a resistive heater in analternative configuration, such as a resistive mesh positioned at oneend or along the length of the wick. Alternatively, the heater assembly36 could be a resistive heater in the form of a rod or blade projectinginto the reservoir 20. Alternatively, the heater assembly 36 could be acombination of a susceptor in thermal contact with a wick or projectinginto the reservoir 20 and an inductor coil configured to inductivelyheat the susceptor.

The aerosol generated by the aerosol generator 22 is picked up byairflow through the aerosol generating system 10 when air is drawnthrough the airflow outlet 16. The aerosol generator 22 may becontrolled and powered such that aerosol is only generated when theaerosol generating system 10 is drawn upon. A pressure sensor may beincorporated into the control unit 18 to determine when the aerosolgenerating system 10 is drawn upon.

Both of the configurations of the aerosol generator 22 shown in FIGS. 2to 4 may produce a wide range of droplet sizes within the generatedaerosol. To homogenise the droplet sizes within the generated aerosol byremoving or resizing droplets that are above a desired maximum size, inthis first example embodiment of the example embodiments the aerosolgenerating system further includes a perforated plate 24 between theaerosol generator 22 and the airflow outlet 16. During use, aerosolgenerated by the aerosol generator 22 flows towards the perforated plate24. The perforated plate 24 includes a plurality of apertures 54extending through the perforated plate 24. The apertures 54 are about 10micrometres in diameter. The perforated plate 24 is configured to removeor resize droplets with a diameter over 10 micrometres.

FIG. 5 illustrates a perforated plate, in accordance with an exampleembodiment., The perforated plate 24 includes a plurality of alignedfilaments 51. The filaments 51 may be formed of stainless steel. Thefilaments 51 are connected to inner walls of the housing 12 so that theyspan across an entire width of an inner airflow channel extendingbetween the airflow inlet 14 and the airflow outlet 16. In an exampleembodiment, the perforated plate 24 includes a first row of alignedfilaments 52 and a second row of aligned filaments 53, orthogonal to thefirst row to provide a grid of square apertures 54 between the filaments51. In other words, the perforated plate 24 is formed from a meshdefining the plurality of apertures 54.

The aerosol generated by the aerosol generator 22 flows through theperforated plate 24. Droplets within the aerosol that are larger thanthe apertures 54 are blocked by the filaments 51. In this way, theaerosol that exits the airflow outlet 16 does not include any dropletsthat are larger than the apertures 54.

FIG. 6 illustrates a schematic representation of an aerosol generatingsystem, in accordance with an example embodiment. The second exampleembodiment includes many of the same elements as the first exampleembodiment, such as the housing 12 with an airflow inlet 14 and anairflow outlet 16. Like reference numerals are used to designate likeparts. Within the housing 12 is a power supply 13 and control unit 18, areservoir 20 of liquid aerosol-forming substrate 21 and an aerosolgenerator 22. Either of the configurations of aerosol generator 22 shownin FIGS. 2 to 4 could be used in this second example embodiment of theexample embodiments. The second example embodiment of the aerosolgenerating system 60 further includes an electrode 62. The aerosolgenerated by the aerosol generator 22 passes over the electrode 62 asthe droplets of aerosol flow towards the airflow outlet 16 and thedroplets of aerosol are ionized or charged by the electrode 62. Theelectrode 62 may include at least one of a mesh or a ring or a platewith a central hole through which an aerosol can pass. In thisconfiguration, the aerosol is drawn through the electrode 62 by theairflow from an external force on the system. As the droplets of aerosolpass through the electric field created by the electrode 62 the dropletsare ionized. As described herein, the droplets having a diameter above 2micrometres are charged above their Rayleigh Limit. This ensures thatdroplets with a diameter above 2 micrometres break apart as the internalelectrostatic forces overcome the surface tension.

FIG. 7 illustrates a schematic representation an electrode structure, inaccordance with an example embodiment. In one example embodiment, theelectrode may be a nozzle 64. All aerosol generated by the aerosolgenerator 22 must pass through the charged nozzle 64. Therefore alldroplets of the aerosol will pass through the centre of the electricfield created by the electrode 64. The nozzle 64 directs the chargedaerosol towards the airflow outlet 16 to be inhaled. Charging thedroplets of the generated aerosol to a predetermined charge, chosendependent on the liquid aerosol-forming substrate used and known as theRayleigh Limit, ensures that droplets over a predetermined maximum sizebreak apart as the internal electrostatic repulsive forces overcome thesurface tension. Only droplets below the maximum predetermined size exitthrough the airflow outlet 16 to be inhaled.

In a third example embodiment, the features of the first and secondexample embodiments are combined.

FIG. 8 illustrates a schematic representation of a an aerosol generatingsystem, in accordance with an example embodiment.

In an example embodiment, the aerosol is charged by an electrode 62 andalso passes through a perforated plate 24 before being inhaled. Theperforated plate 24 is electrically grounded with respect to theelectrode 62. Droplets charged by the electrode 62 are thereforeelectrostatically attracted to the perforated plate 24 and acceleratetowards the perforated plate 24.

FIG. 9 illustrates a schematic representation of a an aerosol generatingsystem, in accordance with an example embodiment.

. In an example embodiment, the aerosol is charged by an electrode 64and also passes through a perforated plate 24 before being inhaled. Theperforated plate 24 is electrically grounded with respect to theelectrode 64. Droplets charged by the electrode 64 are thereforeelectrostatically attracted to the perforated plate 24 and acceleratetowards the perforated plate 24.

The potential difference between the electrode 62 or 64 and theperforated plate 24, and the distance between the electrode 62 or 64 andthe perforated plate are chosen to provide an electrical field that isinsufficient to cause electrical breakdown of the air between theelectrode 62 or 64 and the perforated plate 24, but may be strong enoughto allow droplets with a diameter over 2 micrometres to be charged toabove the Rayleigh Limit.

FIG. 10 illustrates a schematic representation of a an aerosolgenerating system, in accordance with an example embodiment. An aerosolgenerating system 80 may further include a second reservoir 72 disposedwithin the housing 12. The second reservoir 72 contains an ionizableliquid 73.

FIG. 11 illustrates a schematic representation of the nozzleconfiguration of the aerosol generating system of FIG. 10 , inaccordance with an example embodiment. The aerosol generator 22 ejectsthe liquid aerosol-forming substrate 21 and the ionizable liquid 73, forexample, ethanol, through coaxial nozzles 68 and 65 respectively. Atleast one of the nozzles 65, 68 forms the electrode of thisconfiguration such that the mixture of ionizable liquid and liquidaerosol-forming substrate ejected from the nozzles 65, 68 is ionized.This configuration may improve ionization of a liquid aerosol-formingsubstrate without an ionizable liquid.

In any of the configurations of the third example embodiment of theaerosol generating system 70, 80, the perforated plate 24 may beconnected to the control unit 18 in such a way that any electricalcurrent in the perforated plate 24 can be measured. Alternatively, anelectrical current measuring device or circuit can be providedseparately from the control unit 18. As charged droplets pass throughthe perforated plate 24, the droplets impart their charge to thegrounded perforated plate 24, which will create a current in theperforated plate 24. Therefore, by measuring the current in theperforated plate 24, the rate of droplets passing through the array canbe determined.

The exemplary embodiments described above are not intended to limit thescope of the claims. Other example embodiments consistent with theexemplary embodiments described above will be apparent to those skilledin the art.

1. An aerosol generating system comprising: a housing defining anairflow outlet; a liquid aerosol-forming substrate; an aerosol generatorconfigured to generate an aerosol from the liquid aerosol-formingsubstrate; and an electrode disposed between the aerosol generator andthe airflow outlet, the electrode configured to generate an electricfield which ionizes droplets of the aerosol such that the droplets overa threshold size break apart into smaller droplets.
 2. The aerosolgenerating system according to claim 1, further comprising: a perforatedplate between the electrode and the airflow outlet, the perforated platedefining a plurality of apertures extending through the perforatedplate.
 3. The aerosol generating system according to claim 2, whereinthe perforated plate includes a first plurality of parallel filamentsand a second plurality of parallel filaments, the first plurality ofparallel filaments orthogonal to the second plurality of parallelfilaments so that the plurality of apertures is a grid of apertures. 4.The aerosol generating system according to claim 2 wherein a spacingbetween the electrode and the perforated plate is between 1 millimetreand 50 millimetres.
 5. The aerosol generating system according to claim2, further comprising: a control circuit connected to the perforatedplate and configured to allow measurement of an electrical currentflowing in the perforated plate.
 6. The aerosol generating systemaccording to claim 2, wherein the aerosol generating system isconfigured to generate an electric potential difference between theelectrode and the perforated plate.
 7. The aerosol generating systemaccording to claim 6, wherein the electric potential difference betweenthe electrode and the perforated plate is between 0.5 kilovolts and 30kilovolts.
 8. An aerosol generating system comprising: a housingdefining an airflow outlet; a liquid aerosol-forming substrate; a powersupply; a controller; an aerosol generator configured to generate anaerosol from the liquid aerosol-forming substrate; an aerosol chargingcircuit including a circuit ground and an electrode arranged for fluidcommunication with aerosol generated by the aerosol generator, whereinthe controller is configured to control a supply of electrical powerfrom the power supply to the electrode to charge the electrode to apotential difference of between 0.5 kilovolts and 30 kilovolts withrespect to the circuit ground.
 9. The aerosol generating systemaccording to claim 8, wherein the electrode is a nozzle configured todirect aerosol to the airflow outlet.
 10. The aerosol generating systemaccording to claim 8, further comprising: a perforated plate between theelectrode and the airflow outlet, the perforated plate defining aplurality of apertures extending through the perforated plate.
 11. Theaerosol generating system according to claim 10, wherein a separationbetween the electrode and the perforated plate is between 1 millimetreand 50 millimetres.
 12. The aerosol generating system according to claim10, wherein the perforated plate is electrically connected to thecircuit ground.
 13. The aerosol generating system according to claim 10,wherein the controller is connected to the perforated plate andconfigured to measure an electrical current flowing in the perforatedplate.
 14. The aerosol generating system according to claim 10, whereinthe perforated plate includes a first plurality of parallel filamentsand a second plurality of parallel filaments, the first plurality ofparallel filaments orthogonal to the second plurality of parallelfilaments so that the plurality of apertures is a grid of apertures. 15.The aerosol generating system according to claim 8, further comprising:a first reservoir containing the liquid aerosol-forming substrate and asecond reservoir containing an ionizable liquid.
 16. The aerosolgenerating system according to claim 15, wherein the electrode includestwo coaxial nozzles including a first nozzle configured to eject theliquid aerosol-forming substrate from the first reservoir and a secondnozzle configured to eject the ionizable liquid from the secondreservoir.